Method of making tapered pails



DEC., 11, 1945. P|TTNER METHOD 0F MAKING TAPERED PAILS File@ May 7, 1943 TTNER ATTORNE S- Patented Dec. 11, 1945 s PATENT oFFIcE METHOD OF 'EAI-EBEEV PILS .10h11.A.` Bittner, West View, Pa., assigner; by mesne assignments, to Continental Can Com-1 pany, Inc., New `York, N. Y`., a corporation ol' New York Application-.May n 194e, serial No. .485;983' 4 claims.. (c1. icl-rac).

. Myinvention relates to a method and" appa-ras tus. adapted for use in the-manufacture of paiis,

and similar articles. made of sheety material. The

invention. provides a4 novel meth'od of stretching and manipulating a cylindrical bodyy to give it a. tapered form. As herein illustrated, the inventionis` particularly adapted for stretching the cylindrical sheet metal body4 of a pail or like article toa taperedfornr., I

In the.` manufacture ofi sheetmetal pails or con. tainers of tapered or frusta-conical form, it is customary to cut thel blanks for making.` the bodies; from sheet metal, in an arcor curved' shapev such that when rolled to: bring thel ends of the blank:Y together, the article has thev required tapered form, Owing to the shape of the. blanks, this; method results in. ya large amount` or waste material.

Ana object oi the present invention is; tov avoid such waste.7 and to this end the invention. providesa method by whichthe body of thearticle or container can. be made` in cylindrical form from a straight blank andthereafter stretched and reshaped to glye it: the required tapered. form.

In the. manufacture of sheet. metal bodies; for makingpailsA and the. like, the blank isrolled `and the end edges. are, overlapped and welded to` gether... If it is` attempted to` stretch the cylin drical` body` to a tapered. form, the welded seam presents a diiliculty as the metal at-th'e seam does= not stretch so` readily and there. is a tendency for the seam to give` way under theY strain of' the: stretching operation; such' strain being applied primarily and mainlyv at the end of theseam. This difliculty is increased owing to the usual welding methods, because the weld at the end portion of the seam is comparatively weak. An object of the invention is to provide a method by which th'ese diiliculties are overcome.

Other objects of the invention will appear hereinafter.

Referring to the accompanying drawing:

Fig'. 1 is a perspective view of a cylindrical body designed for use in making a pail.

Fig. 2 is a similar view showing a portion of the rim adjacent the seam curled over.

Fig. 3 is a similar View showing the said body after being stretched to tapered form.

Fig. 4 is a detailed sectional view showing th'e curled rim portion `at the commencement of the stretching operation.

Fig. 5 isa similar View showing the metal partly l uncurled.

Fig. 6 is a sectional elevation of the stretching apparatus.

Fig: Z is a section at the line l-T on Fig. 61.

Referring to the drawing which illustrates the method of' forming the tapered body of a, pail or the like, a cylindrical body Ill` (Figl): is formed? from a rectangular sheet metal' blank rolled' to cylindrical' form with the end edges over lapped and welded to form a seam I Il. A narrow strip I3 comprising the upper end portion ot the seam` is then shearedioff along the dotted line I-`3", in any approved manner, as for example, iny a horn press; The lineA of severance is' slightly curved soA that it cuts the rim I'5- of the cylinder at the `points I2. The rimof the cylinder be# tween the points I2 is then bent over or curled as by means of a curl punch to form a curled lip4 I4 includingthe upper portion of the seam I f'.

By shearing ofi` the strip I3 the weakened endl portion of the seam is removed. The manipulation of the metal in the operation forming the lip I4 softens the metal which has been more or lessl hardened by the sudden chilling of the metalatthe completion yof the Welding operation. softening of the metal 'permits the lip tobe stretched and uncurled when the cylinder is stretched as hereinafter described'. Owing to the lip t4, the stretching force tending to disrupt the seam is transferred from the upper end of the` seam to a point belowA oraway from said end, which greatly reduces the tendency to separate the edges of the metal at the seam.

During this stretching operation, the lip Il is gradually uncurled. Fig. 5 shows the lip partly unrolled at an intermediate stage during thel stretching operation. The uncurling of lip I4 brings the edge thereof up te the level of the cylinder rim. It will be noted that the strip I3 Vwhich is` sheared ofi, is of a depth to compensate for the stretching of the lip I4 so that at the completion of the stretching operation, the rim I5 has been restored to its circular form.

Referring to Figs. 6 and '7, the stretching apparatus comprises a frame 20 on which is bolted a top plate 2 I. Expander ngers 22 are arranged in an annular series and pivotally mounted at their lower ends on a bearing ring 23. The series of fingers is supported within a recess 24 in the plate 2|. The ngers 22 are in the form of flat bars which are preferably close together, so that when in vertical position, their exterior surfaces provide a substantially or approximately continuous cylindrical wall surface.

The set of stretching ngers 22 as a whole, provides an expansible support for holding the sheet metal cylinder I0 during the stretching operation.

The fingers are formed with lugs 25 at their lower ends to -provide a bottom support for the cylinder I0. The upper ends of the lingers are drawn inwardly by a coil spring 26 which extends circumferentially of the group of fingers and is seated in recesses 2'I formed in the upper ends of the lingers.4 4

An expanderl 28 of frusto-conical Yshape is slidably mounted on a vertical rod 29, the lower end of which is connected through a link 3|] to an eccentric or crank on a crank shaft 3I journalled in the frame 20. A spur gear 32 is keyed to the shaft 3| and is driven by a pinion 33. A coil spring 34 mounted on the rod 29 is held under compression between the expander head 28 and a nut 35 threaded on the rod. A stop nut 36 is also threaded on the rod 29 below the head 28.

Operatz'01z.-The expander 28 is moved to its uppermost position which permits the fingers 22 to swing inwardly to a substantially vertical position as shown in dotted lines (Fig. 6). A cylinder I0 is then placed in position with its lower edge resting on the lugs 25. The shaft 3l is then rotated to draw the expander head 28 downward, causing it to act as a wedge or cam for spreading theexpander iingers 22.v The inner surfaces of the ngers which contact with the head 28, are

cent their upper ends, which permits a more nearly uniform rate of stretching of the metah As the rod 29 and expander 28 are moved downwardly, the expander fingers 22 are swung outwardly by the wedging or camming action of the head 28, thereby stretching the walls of the workpiece` so that it is drawn to the tapered form shown in Fig. 3. During this stretching, the curled lip I4 is unrolled or uncurled, bringing it back into conformation with the general contour of the Work-piece.

The lip I4 during the process of its formation is stretched a certain amount in a direction transverse to its length. This would tend to bring the edge of the lip when uncurled, =above the level of the-rim I5. This stretching is compensated for by the removal of the strip I3 prior to the formation of the lip, so that when the lip has been uncurled as above described, it is brought substantially into line with the rim I 5.

' I claim:

1. The method Ywhich comprises rolling a blank of sheet material to cylindrical form with the ends of the blank overlapping, welding said overlapping ends together to form a seam extending lengthwise of the cylinder, curling a portion of the rim of the cylinder which extends across the seam at one end of the cylinder, and applying an expanding force within the cylinder at said endl 2. The method which comprises rolling a blank of sheet material to cylindrical form with the ends of the blank overlapping, welding said overlapping ends together to form a seam extending lengthwise of the cylinder, shearing from the rim at one end of the cylinder a narrow strip including an end portion of said seam, curling the rim of the cylinder outwardly and downwardly along the line of severance of said strip, and thereafter stretching the cylinder to a tapered form in which said end is exipanded, by forces applied in radially outward directionsv to the interior'surface of the cylinder and causing said curled portion to be uncurled by said stretching of the cylinder.

3. The method of treating a body made of sheet material formed by rolling a blank of the material, bringing the ends of the blank together and uniting them in a seam extending from one rim of. said body, which method comprises severing from said body a narrow strip extending along said rim and including an end portion of the seam, curling outwardly the portion of the rim from which said strip has been severed and thereby stretching the material forming said curled portion, and thereafter applying an expansive force to the interior surface of said body along said rim and thereby expanding the material and simultaneously uncurling said curled portion.

4. The method which comprises rolling a blank of sheet metal to cylindrical form with the Vends of the blank brought together,l welding said ends together to form a seam extending lengthwise 'of' the cylinder, applying an annular series of shaping surfaces to the interior surface of the cylinder with each of said shaping surfaces extending lengthwise of the cylinder andfin Contact with said interior surface, said shaping surfaces together forming a substantially cylindrical surface co-extensive circumferentially and lengthwise with said interior surface of the cylinder, swinging allof said shaping surfaces individually and simultaneously outwardly, each about a fixed fulcrum closely adjacent to the lower end oftheV l severed and thereby stretching the metalformingsaid curled portion, and causing said curled portion to be uncurled by said stretching of the,V 

